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It’s a mealybug’s life

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Agricultural officials are breathing a sigh of relief, now that DNA testing has revealed the true identity of a plant pest discovered last month in Cal Poly’s greenhouses.

Initial testing by the California Department of Food and Agriculture had identified the sucking insect as a rare passion vine mealybug, which attacks 300 types of food and commercial plants, including grapes. Since this pest has never been established in the U.S., federal officials quickly moved to place Cal Poly’s greenhouses under strict quarantine to prevent its spread while more mealybugs were collected for analysis.
 
Identification of the 5,000 different species of mealybugs under a microscope is difficult, using a complex scoring system based on characteristics such as the number of tubular ducts and measurements of appendages.
 
Expensive and time-consuming DNA analysis of the mealybugs at federal laboratories in Maryland has now identified the tiny insect as being more closely related to the common, and less threatening, citrus mealybug. “DNA technology will be changing the entomology field—we may see changes in the way insect identifications are made,� says Brenda Ouwerkerk, SLO County’s chief deputy agricultural commissioner.
 
She says agriculture officials “erred on the side of caution� in quarantining Cal Poly’s greenhouses, once routine county inspections revealed the mealybugs. “With so much at stake with California’s agriculture, it was the right thing to do. Cal Poly’s students, staff, faculty, and administration have been extremely cooperative. I’m proud they turned this into a huge learning experience, so students know the impacts and ramifications of bringing in plants.�
 
Horticulture students with plant projects were inconvenienced by the quarantine, which prevented them from entering the greenhouses or selling their crops.
 
Meanwhile, county agricultural inspectors will continue their work looking for plant pests at nurseries throughout the area. Says Ouwerkerk, “The system works. It’s that diligence that keeps California agriculture clean.�


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